Elephants can swim quite well. Although they float, they become almost completely submerged and use their trunks like snorkels. They have been observed swimming to islands off the coast of India, and it has been proposed that they were able to swim from India to Sri Lanka before the island was inhabited by humans.

On Andaman Islands in the Bay of Bengal, loggers who use elephants use to have their elephants swim from island to island. Gracefully paddling through the blue waters of the Andaman, the elephants display remarkable versatility. It is their strength and intelligence that has supported the island timber industry.

But, why do elephants swim so gracefully? New research suggests that the animals evolved from mammals like the sea cow which is still found in some of the world's oceans. Ann Gaeth, at the University of Melbourne, Australia, found that elephant foetuses contained a physiological curiosity called a nephrostome. This is a funnel-shaped kidney duct found only in freshwater fish, frogs and egg-laying reptiles.

The trunks themselves appear extremely early on in foetal development, being shown in even the earliest embryo examined. This suggests that they were used when the elephants' ancestors lived in water, probably as snorkels.

Wildlife photographer Steve Bloom spent some years in the Andaman Islands and photographed the swimming elephants. Some of the images in this post belong to his new book, "Elephant!".

Finally, in the next BBC video, by David Attenborough, you will see african elephants having some fun in water after the dry station. So wonderful.